二刷45

Author: diguage

docs/0045-jump-game-ii.adoc

@@ -1,32 +1,77 @@
 [#0045-jump-game-ii]
-= 45. Jump Game II
+= 45. 跳跃游戏 II
 
-{leetcode}/problems/jump-game-ii/[LeetCode - Jump Game II^]
+https://leetcode.cn/problems/jump-game-ii/[LeetCode - 45. 跳跃游戏 II ^]
 
-Given an array of non-negative integers, you are initially positioned at the first index of the array.
+给定一个长度为 `n` 的 **0 索引**整数数组 `nums`。初始位置为 `+nums[0]+`。
 
-Each element in the array represents your maximum jump length at that position.
+每个元素 `nums[i]` 表示从索引 `i` 向前跳转的最大长度。换句话说，如果你在 `nums[i]` 处，你可以跳转到任意 `nums[i + j]` 处:
 
-Your goal is to reach the last index in the minimum number of jumps.
+* `+0 <= j <= nums[i]+`
+* `i + j < n`
 
-*Example:*
+返回到达 `nums[n - 1]` 的最小跳跃次数。生成的测试用例可以到达 `nums[n - 1]`。
 
-[subs="verbatim,quotes,macros"]
-----
-*Input:* [2,3,1,1,4]
-*Output:* 2
-*Explanation:* The minimum number of jumps to reach the last index is 2.
-    Jump 1 step from index 0 to 1, then 3 steps to the last index.
-----
+*示例 1:*
+
+....
+输入: nums = [2,3,1,1,4]
+输出: 2
+解释: 跳到最后一个位置的最小跳跃数是 2。
+     从下标为 0 跳到下标为 1 的位置，跳 1 步，然后跳 3 步到达数组的最后一个位置。
+....
+
+*示例 2:*
+
+....
+输入: nums = [2,3,0,1,4]
+输出: 2
+....
 
-*Note:*
+*提示:*
 
-You can assume that you can always reach the last index.
+* `1 \<= nums.length \<= 10^4^`
+* `+0 <= nums[i] <= 1000+`
+* 题目保证可以到达 `nums[n-1]`
+
+
+== 思路分析
+
+image::images/0045-10.png[{image_attr}]
 
 
 [[src-0045]]
+[tabs]
+====
+一刷::
++
+--
 [{java_src_attr}]
 ----
 include::{sourcedir}/_0045_JumpGameII.java[tag=answer]
 ----
+--
+
+二刷::
++
+--
+[{java_src_attr}]
+----
+include::{sourcedir}/_0045_JumpGameIi_2.java[tag=answer]
+----
+--
+
+二刷（优化）::
++
+--
+[{java_src_attr}]
+----
+include::{sourcedir}/_0045_JumpGameIi_20.java[tag=answer]
+----
+--
+====
+
+
+== 参考资料
+
 

docs/images/0045-10.png

@@ -718,6 +718,11 @@ endif::[]
 |{doc_base_url}/0026-remove-duplicates-from-sorted-array.adoc[题解]
 |✅ 双指针
 
+|{counter:codes2503}
+|{leetcode_base_url}/jump-game-ii/[45. 跳跃游戏 II^]
+|{doc_base_url}/0045-jump-game-ii.adoc[题解]
+|✅ 贪心算法。也可以动态规划。
+
 |===
 
 截止目前，本轮练习一共完成 {codes2503} 道题。

logbook/202503.adoc

@@ -35,6 +35,9 @@ public class _0045_JumpGameII {
      * Runtime: 1 ms, faster than 99.98% of Java online submissions for Jump Game II.
      *
      * Memory Usage: 36.4 MB, less than 100.00% of Java online submissions for Jump Game II.
+     *
+     * @author D瓜哥 · https://www.diguage.com
+     * @since 2019-10-26 11:29
      */
     public int jump(int[] nums) {
         if (Objects.isNull(nums) || nums.length == 0) {

src/main/java/com/diguage/algo/leetcode/_0045_JumpGameII.java

@@ -0,0 +1,30 @@
+package com.diguage.algo.leetcode;
+
+import java.util.Arrays;
+
+public class _0045_JumpGameIi_2 {
+  // tag::answer[]
+
+  /**
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2025-05-17 21:14:27
+   */
+  public int jump(int[] nums) {
+    int length = nums.length;
+    int[] dp = new int[length];
+    Arrays.fill(dp, length + 1);
+    dp[0] = 0;
+    for (int i = 0; i < length; i++) {
+      int min = Math.min(length - 1, i + nums[i]);
+      for (int j = i + 1; j <= min; j++) {
+        dp[j] = Math.min(dp[j], dp[i] + 1);
+      }
+    }
+    return dp[length - 1];
+  }
+  // end::answer[]
+  public static void main(String[] args) {
+    new _0045_JumpGameIi_2()
+      .jump(new int[]{2, 3, 1, 1, 4});
+  }
+}

src/main/java/com/diguage/algo/leetcode/_0045_JumpGameIi_2.java

@@ -0,0 +1,31 @@
+package com.diguage.algo.leetcode;
+
+public class _0045_JumpGameIi_20 {
+  // tag::answer[]
+  /**
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2025-05-17 21:14:27
+   */
+  public int jump(int[] nums) {
+    int length = nums.length;
+    int max = 0;
+    int step = 0;
+    int end = 0;
+    for (int i = 0; i < length; i++) {
+      max = Math.max(max, i + nums[i]);
+      if (max >= length - 1) {
+        return step + 1;
+      }
+      if (i == end) {
+        end = max;
+        step++;
+      }
+    }
+    return step;
+  }
+  // end::answer[]
+  public static void main(String[] args) {
+    new _0045_JumpGameIi_20()
+      .jump(new int[]{2, 3, 1, 1, 4});
+  }
+}